Supon Ananta

Scaling behavior of dynamic hysteresis in soft lead zirconate titanate bulk ceramics

The scaling behavior of the dynamic hysteresis of ferroelectric bulk system was investigated. The scaling relation of hysteresis area ⟨A⟩ against frequency f and field amplitude E0 for the saturated loops of the soft lead zirconate titanate bulk ceramic takes the form of ⟨A⟩∝f−1∕4E0, which differs significantly from that of the theoretical prediction and that of the thin film. This indicates that the scaling relation is dimension dependent and that depolarizing effects in the interior must be taken into account to model bulk materials. Additionally, the scaling relation for the minor loops takes the form of ⟨A⟩∝f−1∕3E03, which is identical to that of the thin film as both cases contain similar 180° domain-reversal mechanism.

Temperature scaling of dynamic hysteresis in soft lead zirconate titanate bulk ceramic

The temperature scaling of the dynamic hysteresis was investigated in soft ferroelectric bulk ceramic. The power-law temperature scaling relations were obtained for hystersis area ⟨A⟩ and remnant polarization Pr, while the coercivity EC was found to scale linearly with temperature T. The three temperature scaling relations were also field dependent. At fixed field amplitude E0, the scaling relations take the forms of ⟨A⟩∝T−1.1024, Pr∝T−1.2322, and (EC0−EC)∝T. Furthermore, the product of Pr and EC also provides the same scaling law on the T dependence in comparison with ⟨A⟩.

Effects of uniaxial stress on dielectric properties lead magnesium niobate?lead zirconate titanate ceramics

Effects of uniaxial stress on the dielectric properties of ceramics in lead magnesium niobate?lead zirconate titanate (PMN?PZT) system are investigated. The ceramics with a formula (x)Pb(Mg1/3Nb2/3)O3?(1?x)Pb(Zr0.52Ti0.48)O3 or (x)PMN?(1 ? x)PZT when x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0 are prepared by a conventional mixed-oxide method. Phase formation behaviour and microstructural features of these ceramics are studied by x-ray diffraction and scanning electron microscopy methods, respectively. The dielectric properties under the uniaxial stress of the PMN?PZT ceramics are observed at stress levels up to 5?MPa using a uniaxial compressometer. It is found that with increasing applied stress the dielectric constant of the PZT-rich compositions increases slightly, while that of the PMN-rich compositions decreases. On the other hand, the dielectric loss tangent for most of the compositions first rises and then drops with increasing applied stress.

Dynamic hysteresis and scaling behavior of hard lead zirconate titanate bulk ceramics

The scaling relation of ferroelectric hysteresis area ⟨A⟩ against frequency f and field amplitude E0 for the saturated loops of the hard lead zirconate titanate bulk ceramic takes the form of ⟨A⟩∝f−0.28E00.89, while that for the minor loops takes the form of ⟨A⟩∝f−0.43E03.19. In both cases, the scaling relations are similar to those of its soft counterpart. This indicates that the dynamic behaviors and scaling relations in bulk ceramics are mainly governed by the domain states and structures, while the distinct types of complex defects contribute mainly to the difference in the coercive field observed in hard and soft ceramics.

Dynamic ferroelectric hysteresis scaling of BaTiO3 single crystals

The scaling behavior of the dynamic hysteresis of ferroelectric BaTiO3 single crystals was investigated. Two sets of the scaling relation of hysteresis area ⟨A⟩ against frequency f and field amplitude E0 were clearly established. Above the coercive field, the scaling took a form of ⟨A⟩∝f−0.195E00.950. On the other hand, the scaling in the form of ⟨A⟩∝f1.667E0−2.804E04.157 was obtained under subcoercive field condition. While these scaling relations were generally comparable to previously reported ones, it was found that the f and E0 exponents depended on E0 and f, respectively, which was in contrast to the prior theoretical prediction and experimental investigations.

Synthesis, formation and characterization of zirconium titanate (ZT) powders

Zirconium titanate (ZrTiO4) powders have been prepared and characterised by differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) techniques. The effect of calcination temperature, dwell time and heating/cooling rates on phase formation, morphology and particle size distribution of the powders are examined. The calcination temperature and dwell time have been found to have a pronounced effect on the phase formation and particle size of the calcined zirconium titanate (ZT) powders. It has been found that the minor phases of ZrO2 and TiO2 tend to form together with ZrTiO4, depending on calcination conditions. Optimisation of calcination conditions can lead to a single-phase ZrTiO4 in an orthorhombic phase. D 2002 Elsevier Science B.V. All rights reserved.

Effect of calcination conditions on phase formation and particle size of nickel niobate powders synthesized by solid-state reaction

Abstract The solid-state mixed oxide method via a rapid vibro-milling technique is explored in the preparation of single-phase nickel niobate (NiNb 2 O 6 ) powders. The formation of the NiNb 2 O 6 phase in the calcined powders has been investigated as a function of calcination conditions by TG-DTA and XRD techniques. Morphology, particle size and chemical composition have been determined via a combination of SEM and EDX techniques. It has been found that the minor phases of unreacted NiO and Nb 2 O 5 precursors and the Ni 4 Nb 2 O 9 phase tend to form together with the columbite NiNb 2 O 6 phase, depending on calcination conditions. More importantly, it is seen that optimization of calcination conditions can lead to a single-phase NiNb 2 O 6 in an orthorhombic phase.

Change of dielectric properties of ceramics in lead magnesium niobate-lead titanate system with compressive stress

Effects of compressive stress on the dielectric properties of PMN?PT ceramics were investigated. The ceramics with the formula (1 ? x)Pb(Mg1/3Nb2/3)O3-(x)PbTiO3 or (1 ? x)PMN?(x)PT (x = 0.1?0.5) were prepared by a conventional mixed-oxide method and then characterized with x-ray diffraction (XRD) and scanning electron microscopy. Dense perovskite-phase PMN?PT ceramics with uniform microstructure were successfully obtained. The dielectric properties under compressive stress were observed at stress up to 230?MPa using a home-built compressometer. The experimental results revealed that the superimposed compression stress significantly reduced both the dielectric constant and the dielectric loss tangent of 0.9PMN?0.1PT ceramic, while the changes were not as significant in the other PMN?PT ceramic compositions. In addition, the dielectric properties were considerably lowered after a stress cycle. Since change in the dielectric properties with applied stress was attributed to the competing influences of the intrinsic and the extrinsic contributions, the observations were mainly interpreted in terms of domain switching through non-180? domain walls, de-ageing, clamping of domain walls and the stress induced decrease in the switchable part of spontaneous polarization.

Stress-dependent scaling behavior of dynamic hysteresis in bulk soft ferroelectric ceramic

The effects of frequency f, field amplitude E0, and mechanical stress σ on the hysteresis area ⟨A⟩ and their scaling relations were investigated on soft PZT bulk ceramics. The hysteresis area was found to depend on the frequency and field amplitude with a same set of exponents to the power-law scaling for both with and without stresses, indicating the universality. The inclusion of stresses into the power law was also obtained in the form of ⟨A−Aσ=0⟩∝f−0.25E0σ0.44, which indicates the difference of the energy dissipation between the under stress and stress-free conditions and reveals how the hysteresis area decays with increasing stresses.

A modified two-stage mixed oxide synthetic route to lead zirconate titanate powders

Abstract An approach to synthesis lead zirconate titanate [Pb(Zr1−xTix)O3; PZT] powders with a modified two-stage mixed oxide synthetic route has been developed. To ensure a single-phase perovskite formation, an intermediate phase of zirconium titanate (ZrTiO4) was employed as starting precursor. The formation of perovskite phase in the calcined PZT powder has been investigated as a function of calcination temperature, soaking time and heating/cooling rates by differential thermal analysis (DTA) and X-ray diffraction (XRD) techniques. The morphology evolution was determined by scanning electron microscopy (SEM) technique. It has been found that the unreacted PbO and ZrTiO4 phases tend to form together with PZT, with the latter appearing in both tetragonal and rhombohedral phases, depending on calcination conditions. It is seen that optimisation of calcination conditions can lead to a 100% yield of PZT in a tetragonal phase.